-다니(요): Disbelief and Incredulity

Some Korean endings don't add facts — they add feelings about facts. -다니(요) is the purest example. It takes a piece of information you've just heard or just realized, holds it up at arm's length, and reacts to it with disbelief, dismay, or astonishment: "What?! You're telling me…?! / I can't believe…!". It is never neutral. The moment you attach -다니, you've announced that this information clashes with what you expected — and that clash is the entire point.

Where the disbelief comes from

-다니 is a shortened quotation folded back on itself: -다(고 하)니 — literally "given that (someone says) …". You are echoing a report, but instead of relaying it flatly, you recoil from it. English does exactly the same move with its incredulous echoes: "You're telling me he's already gone?!" repeats the information back with the surprise built in. That echo-with-shock is what -다니(요) grammaticalizes into a single ending.

Notice the second one: -다니 doesn't only carry bad-news dismay. It marks any strong clash with expectation, admiring surprise included. The unifying thread is "this is not what I expected, and I'm reacting to it."

Building the form by sentence type

Because -다니 grows out of quotation, its shape tracks the kind of clause you're reacting to — the same pattern that governs all indirect quotation.

For ordinary verb and adjective statements, attach -다니 to the plain form.

When you're reacting to something built on the copula 이다, use -(이)라니 — the same 이라 you see throughout the quotation system.

A relayed question you can't believe someone asked takes -냐니, and a command takes -(으)라니.

Standing alone or leading into a reaction

-다니(요) is flexible about what comes next. It can stand entirely on its own as an exclamation — the clash is so complete that no further comment is needed — or it can lead into a reaction clause that spells out your response, as in 비싸다니 믿을 수가 없어요 ("it's that expensive, I can't believe it") above. Both are natural; the standalone version is more punchy and emotional.

Register: the 요 is what makes it polite

As with every sentence-final ending in this family, -다니 alone is intimate 반말, and the polite version simply adds 요. Because -다니 pours out raw emotion, learners instinctively feel it's "just an exclamation" and forget to raise the register. But an incredulous 벌써 갔다니? aimed at your boss is 반말, not politeness — you need 갔다니요?.

Don't confuse it with insistent -다니까

There's a near-twin that means the opposite thing. -다니까(요) is the insistent ending — "I'm telling you! / like I said!" — used when you're repeating yourself with a little exasperation. -다니 recoils at new information; -다니까 hammers home your own point. They look almost identical, so keep the difference sharp: 바쁘다니 means "busy?! (I can't believe you're busy)"; 바쁘다니까(요) means "I told you I'm busy!".

The force is in the intonation

-다니(요) is almost never said flatly. It rides a sharp, rising-then-stretched incredulous contour — the spoken equivalent of wide eyes. That prosody does as much work as the ending itself: 벌써 갔다니요 muttered in a monotone would sound like a half-finished sentence, but delivered with the vowel drawn out it unmistakably means "wait — already?!". Attach -다니 and keep your voice flat, and the disbelief you intend won't land. Say it like you mean it.

Common Mistakes

1. Treating -다니 as a neutral "that…". -다니 is never a plain report; it always carries disbelief. If you just want to relay a fact, use -대요.

2. Dropping 요 upward — the flagship register slip. Bare -다니 to a superior is intimate.

3. Confusing reactive -다니 with insistent -다니까. If you mean "I'm telling you!", you need -다니까(요), not -다니.

4. Using -(이)라니 vs -다니 wrongly with 이다. A reaction to a copula statement takes -(이)라니: 학생이라니, not 학생이다니.

Key Takeaways

• -다니(요) reacts to just-heard or just-realized information with disbelief, dismay, or astonishment — "the very idea that…!". It is never a neutral report.
• Form tracks sentence type: statements → -다니, copula → -(이)라니, questions → -냐니, commands → -(으)라니.
• For a plain, feeling-free relay, use -대요/-래요 instead.
• Don't confuse it with insistent -다니까(요) ("I'm telling you!") — same look, opposite job.
• Upward, add 요; bare -다니 is 반말.